Electrode composition



ELECTRODE COMPOSITION Gerald G. Hatch, Chicago, Ill., assignor toKennecott Copper Corporation, New York, N. Y.

Original application May 31, 1950, Serial No. 165,346,

now Patent No. 2,676,882, dated April 27, 1954. Divided and thisapplication June 23, 1953, Serial No. 371,092

1 Claim. (Cl. 29-191.2)

The present invention is particularly adapted to a method for therecovering of elementaltitanium from a reaction mixture produced inaccordance with the method disclosed in Glasser and Hampel applicationSerial No. 90,954, entitled, Method for the Production of Titanium, andassigned to the same assignee as the present application. It will berealized, however, that the features of the invention may be utilized inconnection with the recovery of refractory metals other than titanium,such as, for example, zirconium, beryllium, chromium, cobalt, manganese,molybdneum, nickel, platinum, silicon, tungsten, and the like, and thatit will also be applicable to the recovery of refractory metals fromadmixture with salts of reducing metals such as sodium, potassium,lithium, calcium, strontium, barium, and magnesium.

Briefly, the above-described process consists in reacting liquidtitanium tetrachloride with an alkali metal amalgam such as sodiumamalgam to form a reaction product containing powdery titaniumparticles, sodium chloride, to- Vgether with any sub-halides to titaniumproduced in the reaction, as well as residual mercury. Since the sodiumcontent of the original amalgam is generally quite low and since anexcess of sodium in the amalgam with respect toV titanium tetrachlorideis used, large quantities of mercury appear in the reaction product. Theremoval of such large quantities of mercury is a considerable task,since the mercury adheres readily to the reaction product. While themercury can be removed by distillation or gravity filtration, these arevery time-consuming and expensive operations.

With the foregoing in mind, an object .of the present invention is toprovide a convenient method for the recovery of refractory metal fromadmixture with compounds having lower fusing points than the metal.

Yet another object of the present invention is to provide a compressedmixture of titanium metal and sodium chloride crystals from whichtitanium metal can be readily recovered, and which is stable in air,water, and other reagents. n

Other objects and features of the present invention will be apparentfrom the following description and the appended claim.

The method of the present invention generally consists ;o,f compressingthe reaction product from the amalgam reaction, which will containpowdery titanium,` mercury, and sodium chloride under elevatedtemperatures to thereby squeeze out all or a major portion of themercury present and also substantial quantities of the sodium chloride.This compression is eifected in the presence of an inert gas such asargon, helium, neon, krypton, and the like, under substantiallyatmospheric pressures. The reaction mixture is compressed to a coherentshape preferably containing at least 35% by weight titanium with thebalance being essentially sodium chloride. This mixture can then betreated for the recovery of metallic z method described in my copendingapplication Serial No. 165,347, now abandoned, filed concurrentlyherewith. Another method for the recovery of titanium from such amixture which may be used is the vacuum distillation of the sodiumchloride present. In addition, the rod can be conveniently melted in aninduction furnace where the sodium chloride is removed byvolatilization.

The advantages of the present invention are quite substantial. For one,the compression of the titanium into coherent form directly upon removalfrom the reaction zone removes the tendency for the titanium to becomecontaminated, since the Vcrystals of Vtitanium are compressed into amuch less reactive form Vthan the submicroscopic particles which areproduced by the reaction. Further, vacuum conditions are not essentialin the 'removal'of mercury and sodium chloride according to Vthe presentinvention, but such removal may be effected in the presence of an inertgas at substantially atmospheric pressures. The process also has theadvantage of flexibility in that it can be made part of a continuous orsemicontinuous process by using the process of the present in,

has been made to the use of gravity type filters or distil- Y lation toremove most of the mercury prior to the treatment of the reactionmassfor the removal of sodium chloride.k By removing the sodium chloride inaccordance with the present invention, a considerable amount of heat issaved, since the heat required is only sufficient to melt the sodiumchloride and not necessarily to vaporize it.

Another advantage which can be realized by the practice of the presentinvention is the convenience by which titanium alloys can be prepared.Thus, the alloying elements may beradded to the reaction mass prior tothe compression step before the removal ofv mercury and sodium chloride,and the alloying elements are carried through the compression step intothe final compressed mixture. Y p

A very important advantage arising from the present invention is thatthe titanium rod or pencil which is produced as a result of thecompression contains agglom,y

. erated particles of titanium which are sul'liciently large titanium inany one of a number of manners. For ex- 7 ample, the mixture may beintroduced into an arc melting furnace as a consumable electrodeaccording to the to be stable upon exposure to air. Thus, thecompressed' product may be stored for indefinite periods priorto furthertreatment.

While the foregoing description of the process wa's con-l cerned withthe recovery of elemental titanium by a reaction involving reductionwith a sodium amalgam, itV

will be appreciated that the same process can be applied to the recoveryof other reactive metals, such as zirconium, which, in finely dividedform, are extremely reactive to air, oxygen, nitrogen and aqueousliquids. mentioned previously, the process is also applicable to therecovery of titanium'and other refractory metals from Y Figure 1 is across-sectional view of y 'an-,apparatusde-fv signed Vto carry out theprocess of the present invention; and

Figure 2 is a fragmentary cross-sectional view of the lower portion ofthe apparatus showing the conditioner thebeginning of the compressionoperation,

As shown on the drawing:

Patented June 1Q, 1958 Y Another 'type is illustrated in the- Referencenumeral denotes generally a casing consisting of an outer jacket 11 andan inner casing 12. The inner casing 12 has aninlet 13 formed thereinfor receiving the products from the reaction. zone which will normallycomprise a large percentage of mercury, sodium chloride, and titaniummetal in the form of a very line powder. Below the inlet 13, there is acylindrical reservoir portion 14 having a relatively large number ofperorations 15 therearound. For the sake of better illustra-l tion, thesize of the perforations 15 has been exaggerated in the drawings, as theactual size of such pcrforations will normally be less than abouti/s ofan'inch in diameter.

The inner casing' 12 below the reservoir portion 14 is formed with atapered perforatedV wall lportion 16. The tapered wall portion 16terminates in a restricted orifice 17 having a perforated conduit 13depending therefrom. A batiie 19 is disposed between the tapered wallportion 16 and the outer jacket 11, and a second battle 20 between theconduit 13 and the jacket 11 are provided `for purposes which will behereinafter described.

At the base of the outer jacket 11 andthe perforated conduit 18, is acylindrical member 21 having a base ange 22 which' can be secured to theinlet of an are melting furnace where the compressed product is to beused as a consumable electrode in an arc melting process. An inlet 23and an outlet 24 are provided along the cylinder 21 for circulating an.inert gas such as argon and the like Within the cylinder 21. A coolingcoil 25 around the base of the cylinder 21 is provided to aid infreezing the compressed mixture after the removal of some of its sodiumchloride content.

The top of the casing 12is provided with a peripheral flange portion 26to which is secured ay closure member 27, asV by means of bolts 28. The.closure member 27 is provided with an inlet 29 for introducing an inertgas of the type described within the casing 12. A 'boss 30 on the'closure member 27 has an axial bore therethrough for slidably receivinga shaft' 31 carrying a plunger 32. The diameter of the plunger 32 isonly slightly smaller than the interior diameter of the casing 12 sothat the plunger 32 is freely reciprocable within the reservoir portion14 of the assembly, and permits the inert gas from the inlet 29 to owpast the plunger 32.

The casing 16 and its adjuncts are disposed within a furnace 35 having aplurality of spaced heating elements 36 therein which control thetemperature of the furnace. Provision should be made for independentlycontrolling the temperatures attained by the various heating elementssince it is desirable to operate the upper section of the furnace at asubstantially lower temperature than the bottom of the furnace.

The operation of the apparatus shown in Figure 1 will now be described.The furnace temperatures are adjusted so that the temperature at thetapered wall portion 16' of the casing is below the melting point lofsodium chloride, and normally within the range from room temperature ofl500 F. and preferably from 600 to 1500 F. The lower portion of thefurnace is operated at a somewhat higher temperature, so that thetemperature below the restricted orifice 17 is above the melting pointof sodium chloride, and, where the system is operated under anatmospheric pressure of argon, this temperature will be in the rangefrom about 1500 to 1800 F. However, these ranges of temperatures mayoverlap, as long as a suticiently long section o f the apparatus isoperated at a temperature above the melting point of the salt to beremoved.

A supply of reaction products ,from the amalgam reaction zone isintroduced into the casing through the inlet 13 Vand is compressed bydownward strokes of the plunger 32 against the tapered side wall 16 andassault through the orifice 17 of the inner casing 14. The tapered sidewall 16 effectively magnies the compressive force exerted by the plunger32 so that `most of the mercury is removed before the reactionmixturepasses `through 4 .t the orice 17. The mercury is removed bygravity flow through a downwardly inclined discharge pipe 40 formed inthe outer jacket 11 and extending through the furnace 35.

The mixture entering the restricted orifice 17 is free or substantiallyfree from mercury, and consists essentially of titanium crystals andsodium chloride. Since the temperature occurring below the orifice 17 isabove the rneltingpointV of sodium. chloride, further compression of themixture at these temperatures causes the sodium chloride toflow throughthe perforations in the conduit 18 fand accurnmulate on the balile 2|),`from which' it', may' be drained through a discharge conduit 41' incommunication therewith. Sodium chloride is remarkably uid attemperatures even slightly above its melting point, so that a largeamount of the sodium chloride present can be removed through thecompression operation. lt will be understood that the process can becarried ,out to remove practically all of the sodium chloride, but thisis not usually the most economical mode of procedure.

'In normal instances, enough sodium chloride will be removed during thecompression to form a mixture of titanium and sodium chloride having atleast 35% by weight titanium. A suitable rod for use as a consumableelectrode in an arc melting process is prepared by carrying out thecompression of the mixture until a compact containing about titanium and25% sodium chloride remains.

The compressed product, as illustrated in Figure 1, is in the form of aself-sustaining rod 42. The. compression 0f the titanium crystals at theelevated tem? peratures used for removing sodium chloride vis suicientto agglomerate very tine particles of titanium metal originally presentinto a stable form so that the finished rod 42 is stable in air may bestored for extended periods prior to Vrecovery of metallic titaniumtherefrom. To facilitate the freezing of the extruded mixture o ftitanium and sodium chloride crystals after the removal of substantialportions of the sodium chloride, the cooling coils 25 are provided witha circulating cooling medium suchas water.

"The apparatus shown in'Figure l is show n `in the coursel of acontinuous extrusion operation wherethe rod- 42 is continuously fedthrough the flange 22 of the cylinder 21'. To initiate the originalcompression, an anvil 45 (Fig. 2) having a base portion 46 secured tothe ange 22 by meansV of bolts 47 is inserted within the cylinder 2.1.The anvil 45 has a tapered upper end portion 48 arranged to be snuglyseated within the `bore of the cylinder 21. The anvil 45 is maintainedin this position until a sufficient amount of the reaction. product hasbeen introduced into. the system and the plunger 32 has compressed themass until the compressed mixtureV at the `base of the .conduit 18 issuiciently rigid to form a self-sustaining structure. Thereupon, theanvil` 45 is removed Vand the extrusion may be operatedV continuously asillustrated ,inFigure l.

The reduction in volume of the reaction product within the apparatus Iisquite substantial, being on the order of 20 times or more.

While the present invention hasV been described primarily with respecttojtreating a reaction product conf,

may .be ejected without departingfrom the scope of theV no vel ,concepts.of the present invention.

I claim as my invention:

A consumable electrode comprising a rod of a compressed mixture of about75% by weight of titanium particles and about 25% by weight of sodiumchloride, the titanium particles being suiciently large to be stabletoward air.

References Cited in the le of this patent UNITED STATES PATENTS2,205,854 Kroll June 25, 1940 2,522,679 Kroll Sept. 19, 1950 2,564,337Maddex Aug'. 14, 1951 2,621,121 Winter Dec. 9,' 1952 OTHER REFERENCESPreparation and Properties of Ductile Titanium, R. S.

Dean et al. pages 1-13, Metals Technology, Technical Publication 1961,February 1946 by American Institute of 5 Mining and MetallurgicalEngineers.

U. S. Air Force Project Rand, Titanium & Titanium- Base Alloys,published Mar. 13, 1949 by the Rand Corp. Santa Monica, Calif., pages52-58 inclusive.

Journal of Metals, April 1950. Ductile Titanium,

10 Vpages 634-64O inclusive by Maddex et al., page 640 relied upon.75-84.

